Name :	Trojan-Spy:W32/Banbra.RM
Detection Names :	Trojan-Banker.Win32.Banbra.fvy Trojan-Spy:W32/Banbra.RM Gen:Trojan.Heur.@hZ@r59IYapOd
Aliases :	Mal_Banker (Symantec)
Size:	4485901
Category:	Malware
Type:	Trojan-Spy
Platform:	W32

This type of trojan secretly installs spy programs and/or keylogger programs.

File System Changes
Creates these files:




Process Changes
Creates these processes:




Network Connections
Attempts to download files from:



Attempts to connect with HTTP to:




Registry Modifications
Sets these values:



Creates these keys:

This trojan steals any information related to Brazilian Internet banking websites. The trojan uses a legitimate malware removal tool to maliciously remove some forms of security software that some Brazilian Internet banking websites require. The removal of the security software paves the way to allow the trojan to steal a user's credentials; the stolen credentials can then be forwarded to a remote server for further malicious use.

The trojan targets popular Brazilian Internet banking websites, such as:


The trojan will also attempt to download and execute files from a remote server.

Execution

Upon execution, the trojan first drops a copy of itself as


It then downloads and executes the legitimate removal tool, Avenger by Swandog. It also creates a number of files to facilitate the smooth execution of its activity. For example, %windir%\system32\drivers\workray.sys is a driver file used by Avenger to operate normally. 





Avenger will be executed in quiet mode, using the tool's parameter, avenger.exe /nogui C:\systemX86.txt. The legitimate files that will be removed by Avenger are specified on the text file, C:\systemX86.txt.

Of particular interest is GbPlugin, a program used by Brazilian banks to protect customers when they perform Internet banking transactions. Though normally difficult to remove, using the Avenger program allows the trojan to remove the GbPlugin at the next system startup or reboot.

The following is a typical script used by Avenger to remove files:

Files to delete:


Folders to delete:


The script is stored on %windir%\system32\awou.txt.

After successfully deleting the targeted files, the text file C:\avenger.txt is created, containing the log of the removal process.

Finally, the cleanup script, C:\cleanup.bat, will delete the backup files created by Avenger.


Data Stealing

Once the security measures are removed, the trojan can proceed to its data stealing routine. When the user browses a targeted online banking website, the trojan is able to inject malicious HTML into the webpage. The injection allows the  trojan to capture keystrokes the user enters into the log-in fields of the website, essentially stealing the user's credentials.

The stolen credentials are then sent to a number of e-mail addresses registered under VFEmail and Inbox.com: